We can look at these preferences separately by parties. In the GLES survey, respondents were asked which party they voted for in the 2017 federal elections. We can use this information to distinguish between the preference profiles of voters of different parties. Note that the absolute numbers of self-proclaimed voters are different across parties. Warmer colors denote a higher density of voters in a location only relative to the numbers of voters of that party, not relative to all voters.

Distribution of voters’ ideal points, by party

The figures reveal important differences between the ideal points of voters of different parties:

The AfD is the party with the most extreme distribution of voters, with voters concentrated mainly at the right-wing identity politics edge.

In contrast, voters of all three “old” parties, i.e. the established parties of old West Germany before ca. 1983 – CDU/CSU, SPD, FDP – are concentrated in the center of both distributions.

The Left party’s voters are the most dispersed, with preferences reaching into the right-wing extremes on the societal dimension.

The Green party’s self-proclaimed electorate is the most clearly concentrated “post-materialist”, even though it comprises a solidly center-left mass on both dimensions.

If we compare these distributions to the positions of parties, we find that the SPD is the party that is farthest away from the mass of the distribution of its voters. This is corroborated by statistical analysis: The SPD is the only party for which the distance between a voter’s ideal point and the party’s position is not a significant predictor of vote choice. In other words: Those who voted for the SPD did not vote for the party because it was close to their preferred positions, but despite the fact that it was far away from their ideal points.

More specifically, the political positions of the SPD are too “left” on both dimension for the liking of their voters. Those voters who hold positions similar to those of the SPD vote for either the Greens or the Left party. Given the overall distribution of voters’ preferences, any further moves to the “left” are likely to result in a further decrease of the SPD’s political support.